Field of the Invention
The present invention relates to tools, typically but not necessarily operated by the human hand, the operation of which involves striking or swinging motions which expose the tools to impacts.
Description of Relevant Prior Art
Tools used to strike objects, and features which protect those tools when in use despite their intended functions, are well known. Prototypical striking tools combine a striking mass in the form of a tool head and a handle, attached to the head, with which an operator may control and increase the acceleration of the tool head from a certain distance. This prototypical design, and typical method of use particularly where tool head mass is substantial, creates ample opportunities for the tool to be damaged, e.g., during an overstrike. During an overstrike, the tool head will not impact the target but instead narrowly, yet almost completely, miss the target leaving a portion of the tool handle, immediately proximate to the tool head, to impact the target and suffer greatly increased stress. Over time, a repeatedly-overstruck tool may catastrophically fail turning the tool head into a dangerous projectile. A number of devices have been proposed to help avoid these problems.
One such device is depicted in U.S. Pat. No. 279,582 entitled “Ax and Tool Handle Guard.” Depicted there is a tool collar in the form of a metal sleeve adapted to wrap around a handle near the tool's head. The handle sleeve secures against itself through a set of tongues which engage rivets on the sleeve's surface. Also depicted is a U-shaped collar that wraps around the handle between the sleeve and the tool head, the collar being secured against the handle by a set of teeth. The U-shaped collar prevents the tool head from sliding down the handle when in use and the sleeve, as disclosed, protects the handle “from being split or splintered.”
Another device is depicted in U.S. Pat. No. 661,523 entitled “Protector for Tool Handles.” Depicted there is a shield fitted to one side of a handle, affording limited handle protection. One end of the shield fits between the tool head and the handle and the other end of the shield with an attaching strip.
Another device is depicted in U.S. Pat. No. 1,310,312 entitled “Ax Handle Guard.” Depicted there is a one-piece, sheet metal guard bent to fit around just the front-facing and side surfaces of the handle of an axe near the axe head. The guard covers the handle from below the axe head and up in between the handle and the inner portion of the axe head. The guard is secured to the handle by rivets which extend from one side portion of the guard, through the handle itself, and into the other side portion of the guard.
Yet another device is depicted in U.S. Pat. No. 5,735,630 entitled “Striking Tool Head System and Common Elongated handle for Multiple Tool Head Assemblies.” Depicted there is a tool handle adapted to accept multiple tool head types, those tool heads being secured against the handle with a one-piece sleeve fitting around the entirety of the handle. The sleeve creates a tapered ledge which frictionally mates with the tapered inner surfaces of the tool heads. The tool heads are prevented from advancing off the top end of the handle as a result of the tool head inner surfaces' top apertures having larger diameters than the bottom apertures, and overstrike protection is provided by the portion of the sleeve that exists below the tool head.
The litany of prior art tool devices which have features designed to secure a head onto a handle, protect the portion of the handle that meets the head, or both are only partially successful as they are limited to utilizing friction to secure the head onto the handle, do not protect the full circumference of the handle, or fail to adequately distribute overstrike impact along the length of the handle. A need exists for an improved apparatus and method for securing a head to a tool handle that also provides overstrike protection.